Courtroom drama marked the first week of a high-stakes federal trial underway in Kansas, the outcome of which could encourage or hinder tighter voter registration requirements across the country.

At the center of the lawsuit is Kansas Secretary of State Kris Kobach, one of Donald Trump's key backers on voter fraud and the president's unsubstantiated claims that millions of illegal ballots gave Hillary Clinton the 2016 popular vote.

Kobach led Trump's now-defunct election integrity commission.

Member station KCUR is posting daily updates from the federal courthouse in Kansas City, Kan., where Kobach is trying to prove his claims that voter fraud is widespread.

The judge, George W. Bush appointee Julie Robinson, has repeatedly chastised Kobach and his legal team for failing to submit evidence ahead of trial and then trying to incorporate it into witness testimony.

That's led to heated exchanges, with a frustrated Robinson urging Kobach — who is serving as his own attorney rather than rely on the state's attorney general — to review the basics of federal litigation.

"That's ambushing," she said at one point, and called a fellow Kobach lawyer "out of line."

Kansans who say they were blocked from voting are suing over a law that requires people to show documents like birth certificates or passports to register to vote. The law took effect in 2013.

Lawyers from the ACLU, representing the plaintiffs, say Kobach blocked tens of thousands of legitimate voter applications. The Republican secretary of state — who hopes to be Kansas' next governor — says he is preventing non-citizens from illegally casting ballots.

Kansas is one of two states that require citizenship documentation for voter registration. Kobach's deposition for the trial revealed he planned at one point to speak with Trump about offering incentives to other states to follow suit.

KCUR has this explainer of the lawsuit and the stakes. If Kobach loses his case, it will stop Kansas from enforcing its law on anyone who registers to vote while getting or renewing a driver's license.

The ACLU is arguing so-called "motor voters" are subject to a 1993 federal law that doesn't allow for Kansas' stricter system.

To win, Kobach has to convince the court he's shielding Kansas elections from non-citizens gaming the system. He claims upwards of 18,000 non-citizens could be on Kansas' voter rolls.

He has the names of more than 40 suspected non-citizens who registered to vote and is relying on statistical extrapolations to make his case that they are "the tip of the iceberg."

Rick Hasen, a professor of law and political science at the University of California, Irvine, thinks some Republican states could follow Kansas' footsteps if the court finds in Kobach's favor.

Hasen calls that "red state election law," and says it's based on the theory that making it harder to register ultimately benefits Republicans at the polls. Democrats, meanwhile, see political benefits in easing access to the vote.

"States with Republican legislatures and governors have been passing laws that make it harder to register and vote," Hasen said. "States with Democratic governors and legislatures have been passing laws that make it easier."

This story comes from the Kansas News Service, a collaboration covering health, education and politics across the state.